The disclosure relates to wavelength-division multiplexing and demultiplexing, and more particularly, to WDM optical assemblies using a routing band-pass filter for routing optical signals between multiple optical channel sets.
Wavelength-division multiplexing (WDM) is a technology that multiplexes (e.g., adds) a number of distinct wavelengths of light onto a single optical fiber and demultiplexes (e.g., divides) a number of distinct wavelengths of light from a single optical fiber, thereby increasing information capacity and enabling bi-directional flow of signals. Multiple optical signals are multiplexed with different wavelengths of light combined by a multiplexer at a transmitter, directed to a single fiber for transmission of the signal, and split by a demultiplexer to designated channels at a receiver. By combining multiple channels of light into a single channel, WDM assemblies and associated devices can be used as components in an optical network, such as a passive optical network (PON).
There is an increasing need for faster transceivers, and accordingly, transceivers with more channels (as electronic signal speed cannot increase unlimitedly). However, increasing the number of channels may result in optical signal loss depending on the configuration. For example, beam splitting may provide the ability to deliver signals from one common port to two different subgroups of channel ports, but there may be a significant signal or power loss as a result.
As another example, FIG. 1 is a diagram illustrating a WDM optical assembly 100 including a single WDM common port 102 in optical communication with a single array 103 of eight WDM channel ports 104(1)-104(8) by a plurality of WDM filters 106(1)-106(8) and reflective surfaces 108(1)-108(7). The WDM filters 106(1)-106(8) and the reflective surfaces 108(1)-108(7) are arranged to form an optical path 110 between the common port 102 and each of the eight channel ports 104(1)-104(8). In particular, each of the WDM filters 106(1)-106(8) has a unique passband to allow a portion of the optical signal to pass through the WDM filters 106(1)-106(8) and to reflect the remaining portion of the optical signal towards the reflective surfaces 108(1)-108(7), which in turn reflect the remaining portion of the optical signal towards another one of the remaining WDM filters 106(2)-106(8). In this way, increasing the number of channel ports 104(1)-104(8) increases the number of reflections (i.e., zig-zags) of the optical path 110. Increasing the number of reflections may decrease speed (due to increasing the length of the optical path 110) and may decrease signal quality (as there may be a signal loss each time the signal bounces off of a reflective surface 108(1)-108(7) or if reflective surfaces are slightly misaligned). Accordingly, with the configuration shown in FIG. 1, the more channels that are added, the potential for increased signal loss and slower speeds. Further, with the configuration shown in FIG. 1, more channel ports 104(1)-104(8) may also increase the difficulty, time, and cost of assembling and tuning those channel ports 104(1)-104(8) (with respect to the common port 102).
No admission is made that any reference cited herein constitutes prior art. Applicant expressly reserves the right to challenge the accuracy and pertinency of any cited documents.